The present invention relates to a vector processor and, more particularly, to a vector processor for processing cyclic operation at a high speed.
Recent vector processors adopt the pipeline control method and due to this control, the operation process is divided into conceptual data processing steps referred to as stages and data which should be operated on is inputted to the processor without interruption, thereby realizing a high operating speed. A necessary and sufficient condition for performing high speed processing through the pipelined control is that there is no dependency in operations among the data elements which are used for operation and this is referred to as an "independent" relation.
On the other hand, as shown in the following equation EQU x.sub.i+1 =x.sub.i +a.sub.i (i=0, 1, 2, . . . ) . . . (1)
the cyclic operation or iteration requires a previous result of calculation, so that the "independent" relation is not satisfied. Thus, the data which should be operated on cannot be inputted to the vector processor without interruption and after the output from the processor was generated, this output has to be inputted again to the vector processor. Therefore, control should be made to interrupt the input of the to-be-operated data by clock timings over a number of stages of the vector processor. In the latest super high speed computer, the drop of processing capability of the vector processor with respect to the cyclic operation due to such interruption has decreased to at least a factor of several to a factor of tens as compared with the processing capability compared to other operation of the type which can be "independently" executed. This remarkable deterioration in performance is not limited to only the cyclic operation. In a method of raising the operating speed of the continuous operation processes by conceptually coupling the inputs and outputs of a plurality of vector operations due to the chaining control of the vector processor, such deterioration causes a drawback in that it results in deterioration in performance of the whole subsequent operation process of the cyclic operation.